At the root of health disparities is the diversity in the biological, social, cultural, behavioral, and economic characteristics of individuals and populations. The study of ethnic/racial disparities begins with an understanding of the characteristics of each group and how these characteristics affect cancer development and outcomes. This new application for a joint T32 postdoctoral training program at University of Hawaii Cancer Center (UHCC) and the University of Southern California (USC) Norris Comprehensive Cancer Center (NCCC) addresses cancer health disparities utilizing a unique resource, the Multiethnic Cohort (MEC) Study, a population-based prospective cohort study that has followed African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites for the past 25 years. Linkages to cancer registries, Medicare, and other data sources provide a variety of endpoints for MEC and many other cancer disparity studies conducted at both institutions. The complementary research at UHCC and USC is supported by cutting edge cores and benefits from many years of experience. The specific aims of the proposed training program are: 1. To train postdoctoral fellows for independent careers in cancer research in diverse populations, with a specific focus on the sociocultural, nutritional, lifestyle and biological risk factors leading to cancer health disparities in a variety of ethnic/racial minorities. This program is highly unique and will leverage the long- standing (30+ years) collaboration between research programs at two NCI-designated Cancer Centers to permit a broader experience in training and tools for epidemiological research. 2. To provide extensive applied research experience in a multidisciplinary environment focusing on nutritional, molecular, genetic and translational epidemiology that builds on multiple unique racial and ethnically diverse studies of cancer. Together with strong mentorship, these studies will serve as the centerpiece for an effective transdisciplinary training, which will allow trainees to design innovative high-impact projects, and will prepare trainees for careers in cancer health disparities research. During the 5-year grant period, the training program will educate 8 postdoctoral fellows in Hawaii and 10 in Los Angeles. All trainees will be exposed to a wide range of innovative molecular and traditional cancer prevention approaches (epidemiology, biomarkers, genomics, and nutrition) to address a wide range of cancer disparity research questions across the ethnic/racial populations in Hawaii and California through the close cooperation of mentors in both locations and regular exchange visits. The dual-site training, which regular includes exchange visits, is a particular strength of the proposed training program as it will provide exposure to multi- institutional and multi-disciplinary collaborative research that builds on the expertise and long-standing collaboration between UH and USC in research, education and training.